The present invention relates to a process for the production of carbacycline intermediates from 7-hydroxy-2-oxabicyclo[3,3,0]octan-3-ylideneacetic acid esters. Advantage can be taken of this process to produce stable and pharmacologically active carbacycline derivatives.
DOS [German Unexamined Laid-Open Application] No. 2,912,409 describes a carbacyclin synthesis which starts with a bicyclic lactone and proceeds with an opening of the lactone ring, introduction of an acetic acid ester while forming a dicarboxylic acid ester with preceding hydrogenation, and finally, via cyclization, leads to the carbacycline intermediate. This synthesis not only involves considerable expenditure, but also entails marked losses in yield in its several stages, for example in the introduction of the methyl acetate residue into the open-ring lactone, but especially during the cyclizing of the dicarboxylic acid diester and the subsequent decarboxylation. Thus, there has been a need for an improved process.